Typically, the flow of bulk material downwardly through a hopper is controlled by a discharge valve disposed over an opening in a hopper, bin or other material handling structure. The discharge valve is movable between a closed position where it seats in the opening and an extended position where the discharge valve is elevated over the opening. In the open position, material flows downwardly around the discharge valve in an annulus flow configuration and through the opening in the hopper or other material handling structure.
For the most part, discharge valves of the prior art have assumed the shape of an inverted cone or have been pyrimoidal shaped. Such discharge valves have numerous drawbacks and shortcomings. In many applications employing these prior art discharge valves, the bulk material under certain conditions does not flow efficiently across the surfaces of the discharge valve. Under some circumstances a cone or pyramidal shaped discharge valve is unable to overcome the powder or bulk solids strength or consolidation to induce flow.
Therefore, there has been and continues to be a need for a discharge valve that facilitates a downward annulus flow around the discharge valve and where the upper initial contact surfaces of the discharge valve are designed to facilitate flow from hoppers, silos and other similar material storage or handling structures.